Combines are large self-propelled vehicles used for harvesting and threshing agricultural crop in the field. A harvesting head is typically disposed across the front of the combine vehicle supported on a feederhouse. This harvesting head is configured to cut and convey the crop into the combine vehicle itself where it is threshed, separated, and cleaned.
Traditional harvesting heads included an elongate rigid frame to which harvesting implements are added such as cutter bars, augers, reels, and endless belt conveyors. More recently, the once rigid frame has been replaced by multiple frame sections that are coupled together to pivot with respect to each other.
A typical arrangement has a center frame and left and right wing frames that are coupled to the center frame to pivot with respect to the center frame. This arrangement requires that the other elements in the harvesting head also be pivotable with respect to each other. This multiple pivoting frame arrangement permits wider harvesting heads to more accurately follow the contours of the ground as they are harvesting and therefore to cut more crop.
One problem with this multiple frame arrangement appears in harvesting heads that use endless belt conveyors to convey material. These harvesting heads are commonly called “draper platforms”. As the frame sections pivot with respect to each other the conveyor belts can change their tension until they are damaged due to too much stress. The conveyor belts can also rub against other components if they are lifted or lowered with respect to the frame sections.
U.S. Pat. No. 6,675,668 B2 shows the frame of a multi-section draper platform with three sections (five in FIG. 12) that require a maze of complex linkages and load-balancing elements that extend across the three sections. A frame has forwardly and downwardly extending arms. A table is disposed on the arms. A draper transport system is located on top of the table. It includes including two side drapers and a center adapter section. Pivot pins couple the wing frames to the center frame sections.
U.S. Pat. No. 7,650,736 shows a multi-section draper platform with three sections—a center section and two wing sections—that can be partially folded.
The problem to be solved is that of holding the conveyor belts in the proper position and maintaining a more constant tension in the conveyor belts as the multiple frame sections (upon which the conveyor belts are mounted) pivot with respect to each other during field operations.
These problems are solved by the arrangement described in claim 1. Further advantages are provided by additional claims that are dependent upon claim 1.